Many household products and personal products contain active ingredients which need to be delivered to and deposited on a target surface, i.e., fabric, skin, hair, or teeth. The product must leave the active ingredient (e.g., a perfume or an antimicrobial agent) on the target surface after the product is washed and rinsed off the surface. Since these surfaces are negatively charged, the usual approach for deposition from "leave off" products is to use cationic actives for deposition. Deposition of anionic actives from aqueous solutions onto anionic surfaces can be also achieved by using cationic polymers as deposition aids. For example, cationic polymers can be used to promote the adsorption of artionic surfactants such as sodium dodecyl sulfate onto anionic silica particles. Similarly, cationic polymers may also be used to deposit silica particles onto glass.
Deposition of anionic or nonionic actives onto anionic surfaces from compositions containing anionic surfactants is much more difficult. Unfortunately, a great number of household and personal products (e.g., shampoos, toothpaste, soap bar, and skin cleansing compositions) contain anionic surfactants. Anionic surfactants interfere with deposition by adsorbing on all surfaces as well as forming complexes/precipitates with cationic deposition aids. Even if the deposition occurs, the formulations may exhibit poor stability due to flocculation and precipitation, particularly at high concentration of an anionic active and/or at a high concentration of an anionic surfactant. Silicone oil droplets dispersed in shampoo can be deposited onto hair using a commercially available cationic polymer, Jagua.RTM. available from Rhone-Poulenc. See e.g., European Patent Application 093 601. However, the higher the concentration of an anionic surfactant, the harder it is to attain deposition of actives. Thus, it is desirable to improve the deposition of actives onto a negatively charged target surface in the presence of an artionic surfactant.
There is a need for compositions and methods for effective delivery and deposition of active substances onto negatively charged surfaces, particularly when compositions also contain anionic surfactants.
The use of nonionic "hairy" structures for steric stabilization of particles in different media has been described in "Nonaqueous Silica Dispersions Stabilized by Terminally-Grafted Polystyrene Chains", Journal of Colloid and Interface Science, Vol. 68, No. 1, (January 1979), pp. 190-195. This document, however, does not address the problem of deposition at all. There have been attempts also to use functionalized materials for deposition onto surfaces. (See e.g., U.S. Pat. No. 5, 171,264). These documents, however, do not address the problem of deposition in the presence of anionic surfactants.
Accordingly, it is an object of the present invention to provide a composition for delivery and deposition of an active substance to a target surface while avoiding the disadvantages of the prior art.
It is another object of the present invention to provide compositions for depositing active substances with a negative charge (acquired or inherent) from compositions containing an anionic surfactant, even at high concentrations, onto a negatively charged surface.
It is another object of the invention to provide compositions and methods for depositing active substances onto a target surface, so that the active stays on the surface after the compositions containing the active have been rinsed off.
It is still another object of the invention to provide methods of making and using the compositions for depositing active substances onto a target surface.
These and other objects of the invention will become more apparent from the detailed description and examples that follow.